Altering a compression ratio of a combustion chamber of an engine can improve fuel efficiency of an engine. By increasing a volume of the combustion chamber, the compression ratio is increased, allowing a greater pressure increase in the combustion chamber. In this way, a combustion temperature of the combustion chamber is also increased.
A problem with altering a compression ratio may be increased emissions at higher loads (e.g., mid load). By increasing the compression ratio, and thereby the combustion temperature, NOx emissions may increase. Furthermore, due to an increase the combustion chamber volume, an amount of intake air delivered to the combustion chamber increases. In order to prevent knock, an injection volume may also be increased. As a result of increasing the injection volume, hydrocarbon (HC) emissions may also increase.
Attempts to address the above described issues with regards to altering a compression ratio include an inner piston and an outer piston bounding as shown by Fischer et al. in D.E. 19858245. Therein, the outer piston bounding comprises an adjustable outer piston bounding compression magnitude. The outer piston bounding compression magnitude is adjusted based on the inner piston and a controlled fluid amount between the inner piston and the outer piston bounding.
However, the inventors have found problems with the art described above. In one example, the art can be expensive to construct and implement. As a second example, the art described above does not adequately decrease emissions during increased compression ratio use to mid-load.
In one example, the issues described above may be addressed by a method for adjusting a compression ratio of a combustion chamber via adjusting a volume of the combustion chamber by actuating a control element along a control element axis. A spark plug and/or a fuel injector are arranged on the control element.
As one example, the control axis runs along an axial axis of the combustion chamber with which a piston of the combustion chamber is movable. Therefore, the control element may be actuated closer to or farther from the combustion chamber. Furthermore, the control element may be rotated such that a rotational orientation of the control element, the spark plug, and the fuel injector is changed about the control axis.
In this way, the control element, the spark plug, and the fuel injector may be at a first axial position and a first rotational orientation at a first location while having a second axial position and second rotational orientation at a second location. The first location may be a location of the control element farthest from the combustion chamber, thereby minimizing a compression ratio of the combustion chamber. The second location may be a location of the control element nearest to the combustion chamber, thereby maximizing the compression ratio of the combustion chamber.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.